There is a vast array of flange, fitting, and valve systems, which can be utilized for a multitude of applications. Various industries, of course, each have unique and diverse needs which must be met, and as a result each have preferred systems which function best within their specific applications. Many applications utilize systems, which have fittings and valves that have permanent connections, such as water lines a home, hot water tanks, and underground sprinkler systems. These applications can utilize fittings such as elbows, tees, and crosses, along with valves to control or isolate the water which flows through the lines. These applications typically utilize copper or plastic fittings which can be welded or glued together wherever joints are needed. The seals are leak tight but are typically also permanent such that the seals cannot be made, and then unmade and made again.
In contrast, the subject invention pertains to systems where connections can be assembled, and then disassembled and reassembled again multiple times. Systems needing to incorporate non-permanent seals can utilize flange sealing technologies. Flange sealing having flange seals which can be repeatedly made and unmade are extensive and incredibly diverse in their various approaches to creating a leak tight seal between joints. Certain characteristics and designations can be used to describe them, including sexless and infinitely rotatable.
A sexless flange seal refers to a flange seal where the flanges on each side of a joint are such that any flange on any fitting or valve can mate directly with another as long as they are in the same size category. This can simplify system design. An example of a system that is not sexless is the National Pipe Thread (NPT) technology. This system utilizes fittings with tapered external male threads, which fit into tapered internal female threads. Designers must be constantly vigilant to ensure that the proper interface can occur because of the nature of this system.
An infinitely rotatable flange seal refers to a flange seal where the flanges may be rotated independently of each other and still be able to create a seal, independent of the relative rotation of the sealing flanges. In contrast, many flange systems utilize bolts to mate one flange to another, eg; ASA or ANSI flanges or Con Flat® flanges. As the bolts are tightened the flanges are forced together and compress against a seal. The problem occurs when a certain orientation must occur from one fitting to another. For example, a valve must be installed in a certain position to allow access to open and close it. If the bolted flange on the valve and its adjacent fitting are both fixed, the bolthole orientation of the valve cannot be altered to make this happen. These systems may address this problem by offering rotatable versions of this type flange. Again, the designer must be keenly aware of the potential for orientation problems and be sure to designate which fitting or valve will need to have a rotatable flange and on which end of the component. Infinitely rotatable flange systems do not typically utilize bolts to draw the flanges together against a seal. Drawing the flanges together can be accomplished by using various clamping devices, which allow each flange to infinitely rotated. Orientation of any valve or fitting in relation to the other is easily accomplished and makes design of the system much simpler. Further, clamping devices are typically much easier to assemble and disassemble than bolted style flanges. Examples of this type system are ISO, KF (QF) MF (LF) found in the vacuum/semiconductor industry, and Tri Clover® sanitary fittings often seen in the beverage and dairy industry.
Two materials which are commonly utilized at the point of seal are elastomers and metals. Seals relying on these materials are often referred to as elastomer seals and metals seals. Most applications utilize flange systems which employ a seal between flange connections that is soft, maleable and resilient. It can be used over and over again. Various compound elastomer “O” rings and gaskets are examples of this type seal. Elastomer compounds can be designed to accomplish a seal in various conditions found in a multitude of applications. However, in many cases the conditions may exceed the capabilities of known elastomer compounds. Examples of such conditions include the following:
1. Temperature range—well below 0° F. to 1000+ F.
2. Pressure ranges—10−10 mm of Hg to positive pressure in +100° PSI
3. Exposure to various chemical compounds, either liquid or gaseous, having corrosive properties which may attack the elastomer substance.
Different elastomer compounds have been created to best suit the needs of various applications. However, certain conditions exist, such as with the above examples, which go beyond the capabilities of typical elastomer substances. In particular, there are no elastomer compounds, known to the author, that can withstand certain extreme temperature ranges in either direction, certain chemical corrosives, certain extreme pressures (either vacuum or high positive pressure), and/or combinations of all these conditions. For many of these applications elastomer seals will not work. Extreme applications of this sort can require all metal systems which utilize a metal seal between two metal flanges to create a leak light joint.
Metal flange sealing systems typically utilize a softer type metal between two flanges that compress the softer metal seal between them. A good example of this genre is the Conflat® flange. Extensively used in the high vacuum industry, two sexless, stainless steel flanges are bolted together. A “knife edge” on each flange is pressed into a copper gasket to create a seal. Other systems can utilize various soft metals such as aluminum, zinc, silver, or even gold to accomplish the seal. The ability to withstand more stringent elements of temperature, pressure, or corrosive chemicals is greater with various metals than with typical elastomer compounds. The downside of metal seals is the amount of force (torque) required to make the seal, which usually means a multitude of bolts. This can make assembly and disassembly time consuming and difficult. Further, the seal is typically “deformed” in the sealing process and not normally reusable. Every time a joint is made and unmade a new metal seal is usually required to remake the connection. Further, the soft metals used for seals have the additional problem of becoming too soft at very high temperatures, and can shrink at different rates than the flanges at extremely low temperatures so that sealing can become problematic.